Silver-Coated Cu₂O Nanoparticle Substrates for Surface Azide–Alkyne Cycloaddition

Abstract

Heterogeneous copper nanoparticles (CuNPs) have emerged as a promising alternative to complete the Cu(I)-catalyzed azide−alkyne cycloaddition (CuAAC) owing to better stability and biocompatibility and provide opportunities for surface functionalization of biomolecules. Herein, we fabricated Ag-coated cuprous oxide (Cu 2 O) NP slides to promote dual functions: the metal-enhanced fluorescence effect and external copper ionfree CuAAC reaction. The Cu 2 O NPs were in situ generated on a Ag-coated glass slide, thus accelerating the catalytic process of the surface cycloaddition reaction. Considering the catalytic activity of the Ag-coated Cu 2 O NP surface, the azide−alkyne cycloaddition was studied employing an azido-linked ganglioside GD3 glycan and a caged biotin; the latter surface enabled the detection of fluoride with a sensitivity of 0.82 μM that cannot be used on bare glass slides due to erosion by fluorine. Moreover, the immobilization of antibodies (Ab's) using the BA-tosyl-oriented pathway was further introduced to this newly developed slide surfaces and showed better sensitivity compared to the random Ab immobilization method. The Ag-coated Cu 2 O NP surfaces developed herein represent a practical and alternative sensing platform for biological or diagnostic applications.

Investigating a Boronate‐Affinity‐Guided Acylation Reaction for Labelling Native Antibodies

“…BAs only bind weakly to glycans at neutral pH, and their dissociation constant ( K D ) are in the order of 200–10 5 μM range [26] . However, a K D value of 2.68±0.33 μM (Figure S19) was obtained from Her‐Ab (0–6.6 μM) microarrays fabricated on a BA‐functionalized silver‐coated Cu 2 O nanoparticle glass slide, a surface recently reported for signal enhancement [41] . Notably, no apparent detectable binding was observed for deglycosylated Her‐Ab.…”

Practical Coprecipitation Approach for High-Aspect Ratio Cupric Oxide Nanoparticles: A Sustainable Catalytic Platform for Huisgen and Fluorogenic Click Chemistry

“…We invoked the mechanism based on the following considerations. (i) Much like CuO, it has been shown in several reports that Cu 2 O is also capable of catalyzing the click synthesis. − (ii) However, our optimization studies using Cu 2 O (Table , entry 10) have resulted only in trace amounts of the product. Incidentally, Michaud et al also observed the lack of catalytic activity for Cu 2 O toward click chemistry .…”

Ligand‐assisted imprinting‐probe‐labeling strategy reveals Siglec‐7 ‐ glycoprotein interactions

“…Notably, the cleavage of the labeled protein was not quantitative, as evidenced by the appearance of a faint biotinylated protein band in the corresponding immunoblot image (Lane 3). Notably, because of a considerably high affinity ( K D = 31 nM) between GD3 ligand and rSiglec‐7, [ 29 ] a residual labeled protein was still retained on SBs after the cleavage step (Lane 3, SDS‐PAGE vs. Western blotting). However, no further attempt was made to improve the yield of the cleavage step.…”

“…Given these results, whether the conjugation of a therapeutic payload molecule to rSiglec‐7 would alter the affinity to bind with the natural glycan ligand was determined. Therefore, a GD3 glycan microarray was fabricated, [ 29 ] and the binding affinity of rSiglec‐7 with alkynylated rSiglec‐7 and 3 ‐rSiglec‐7 was compared (Figure 6c). According to fluorescence intensity measurements, alkynylated rSiglec‐7 and 3 ‐rSiglec‐7 exhibited an affinity for GD3 glycan similar to that of original rSiglec‐7, indicating that the modification of rSiglec‐7 does not affect the original binding activity.…”